I will create a new issue for TestProcess#test_too_long_path2 later today. Odd that it's not also failing at ci.rubyinstaller.org

re: potentially using msys-native ruby as BASERUBY rather than build miniruby, this will not work well with the existing rubyinstaller build recipes because the msys environment is not usually persistent. Meaning, msys+mingw are typically extracted into a temp sandbox dir and only used for the build. The sandbox dir is usually deleted after each build. For example, when I build on Win7 32bit I create a 800MiB ramdisk (via imdisk) holding the temp sandbox build dir.